CDs recorded practically two continents apart, these session show how veteran avant trombonists of roughly the same vintage can adapt and collaborate with younger musicians. Each chooses to do so in a different, but very characteristic, fashion.

Giancarlo Schiaffini  born in 1942  is someone whose reinterpretation of the trombones role goes back to the birth of Italian improv with the Gruppo Romano Free Jazz in 1966. Hes an autodidact, who shifts effortlessly between the improv and the notated world. A member of the Italian Instabile Orchestra, he has also involving himself in many jazz situations over the years. Simultaneously he has collaborated with the likes of John Cage, Luigi Nono and Giacinto Scelsi, with specific solo works written for him by Scelsi, Nono and other so-called serious composers.

Thus its no surprise to see him as a member of Impromptu, a Sardinia-based improvisation and composition group, whose members have background in jazz, improv, orchestral and theatrical music. Its unusual line-up adds Schiaffinis trombone to violin  played by Adele Madu plus piano, bass and drums. Cagliari-based pianist Silvia Corda and bassist Adriano Orrù not only teach at the local conservatory but recorded a well-received trio CD under Cordas name a couple of years ago. Drummer and percussionist Roberto Pellegrindi splits his time between hard core improv and conservatory instruction.

Less than six months after the eight tracks on Impromptu were recorded in 2004, London-based trombonist Paul Rutherford  born in 1940  was in Portland, Ore. as part of a free-form concert. His associates were German-born, Vancouver, B.C.-based bassist Torsten Müller, Vancouver-based percussionist Dylan van der Schyff  who has worked with everyone from British reedist John Butcher to American bassist Mark Helias  and Chicago-based tenor saxophonist and clarinetist Ken Vandermark, who in the past decade has probably performed with more different improvisers than anyone else on the scene.

Again, Rutherfords participation in this an ad hoc ensemble is no shock, since from his beginnings in BritImprov, he was as likely to be found in free-form combos like Iskra 1903 with bassist Barry Guy as in such multi-person big bands as Mike Westbrooks or the Globe Unity. He loves to play, whether its with jazz-style bands in the 1980s or, as he has recently, with two live computer processors.

Hoxha includes not a hint of electronics, something which has fascinated Schiaffini in other circumstances as well. Theres also no hierarchical suggestions or Old master - young apprentices separateness here, even though Müller, the next oldest musicians is almost a decade and a half younger than the British trombonist. Instead whats most apparent is a sense of these improvisations being in the moment, which further distances them from Impromptu. That CD consciously specifies the formal strategies that go into individual creations  clearly labeled as written by one or another of the players  even if the end results are all-out improvisations.

Curiously, when timbre follows texture during these fully-rounded performances on Hoxha, Rutherfords slide work and use of mutes at points takes on a gutbucket, traditional jazz coloration, not too distant from the solos of his older contemporary Free Jazzer Roswell Rudd. Trad Jazz was popular in the United Kingdom when Rutherford was coming up and while he, unlike Rudd, was likely never a recorded Dixielander, the fearless technique and casual joy of those older bonemen could influence anyone, even if by osmosis.

Harmonizing Rutherfords sweeps, swoops and echoing timbres with Vandermarks flutter-tongued tenor saxophone rumbles, backed by only bass and drums, also bring up memories of Rudds 1960s strategies with equally strong saxmen like John Tchicai and Archie Shepp. Müllers string-scraping applications, sudden col lengo thrusts and spiccato patterning are the extreme opposite of the steady bassists Rudd worked with in these bands, however. As for van der Schyff, in this situation his thought process is focused more on Free Music than Free Jazz. Hed never be confused with Milford Graves or Beaver Harris. Just listen to the resonation of his cymbal lines, the snaps and rolls on his snares and toms, his slap on unlathed cymbal surface, and the all-encompassing rattles, nerve beats and sand dances he produces from his drum tops. Vandermarks clarinet is another point of demarcation here, since his pinched and nasal trills and woody resonation serves as unmistakable counterpoint to the trombonists echoing purrs and low-pitched elongated slurs.

All this bravura technique surrounding it functions as the prelude and postlude to Baragon, Hoxhas touch-over-21-minutes showpiece. The drummers rattles and raps plus the reedists high-pitched trilling give way to an ample demonstration of the mature Rutherford style as he slides around the slide brace, bell and mouthpiece, crying and shouting through the tube, slithering from harsh note mastication to full-fledged braying and blubbering. During the course of the tune Vandermark plays many roles, at one point creating a sibilant but flowing counter line, broken up with sudden squeaks and shattering tones, and at others  on tenor saxophone creating a tongue-slapping ostinato. Plunger comments and back-of-the-throat squeals are the trombonists response as van der Schyff shifts to rock-like bounces and the bassist wraps things up with an inclusive bass thump.

Impressive for what it is, Hoxha may have benefited from more formalism, something Impromptu, the album, has in spades. But what Impromptu, the band lacks, is a prevailing counterforce to Schiaffani with as powerful an instrument as Vandermarks. As well as she functions, Madus gentler approach to the fiddle is sometimes unintentionally blown away by the Big Bad Wolfness of the trombones power. Conversant with a variety of styles and techniques, pianist Corda mounts a challenge at certain points, but as referee between the front line and the rhythm section, she has to function on both teams.

Often that means the response to brass sound excursions from il dottore Schiaffini is to introduce sparse, isolated timbres. With downwards spiccato slices from the violinist, col legno patterning from Orrù and cascades of passing tones from the piano covering curving plunger tremolos from the trombonist, the end result on a piece like Madaus 11-minute Kaoscasokausa sounds exceedingly solemn and loggy.

Harmonized formalism affects other tunes as well. On Cordas Di poche parole, not only does Pellegrindi appear to be using techniques more appropriate for symphonic kettledrum and bell players than improvisers, but as his sounds expand it seems as if hes valiantly holding himself back from replicating the percussion rumbles from the 1812 Overture. The composer herself falls into near-stereotypical classical chording. Heading for a crescendo of unrelieved tension, the rigidity threatens to throttle the piece. Luckily, a release section of scraped chromatic violin lines and circular stops plus bass string clicks lighten the performance as do jazzy spits and slurs from the trombonist.

Short  less than five minutes  and light-hearted, Schiaffinis Mercoledi 17 rejuvenates the proceedings as do valve slurs, cross patterning piano chords, plucked violin strings and a walking bass line from the players. Following a cymbal resonation that could easily come from pressure on a metal garbage can lid, the tunes extro features tailgate slurs from the composer and swinging slide action from Madau.

Even more exceptional is the final Comme se fosse autunno, evidently a burlesque contrafact of Autumn Leaves. Beginning with double-stopping tremolos from Madau and exaggerated chording that would make Roger Williams proud from Corda, the tune soon develops into a stroll, complete with double-timed, cascading note patterns from the fiddler and a strummed bass lines from Orrù. Following a last minute recapitulation of the theme, the proceedings screech to a sudden halt.

While accomplished, Impromptu the CD, implies that Impromptu, the band, still needs to put more thought into how best to balance its disparate parts. Hoxha, as a one-off improv, misses top rank as well. Still both prove the adage that old trombonists  unlike dogs  can learn new tricks  and get along well enough with musical puppies to pass on their own capers.